diff --git a/TODO-RELEASE b/TODO-RELEASE
index 5629a9c..55371fd 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -9,4 +9,5 @@
 #library	what		description / commit summary line
 libosmo-netif   osmux           new osmux_xfrm_output_* APIs
 libosmo-netif   osmux           new osmux_xfrm_input_* APIs
+libosmo-netif   osmux           new struct osmux_hdr->data[0] field
 libosmo-netif   stream          new APIs osmo_stream_{cli,srv}_clear_tx_queue()
\ No newline at end of file
diff --git a/include/osmocom/netif/osmux.h b/include/osmocom/netif/osmux.h
index f7a5fd5..b6014d5 100644
--- a/include/osmocom/netif/osmux.h
+++ b/include/osmocom/netif/osmux.h
@@ -53,6 +53,7 @@ struct osmux_hdr {
 /* auto-generated from the little endian part above (libosmocore/contrib/struct_endianess.py) */
 	uint8_t amr_ft:4, amr_cmr:4;
 #endif
+	uint8_t data[0];
 } __attribute__((packed));
 
 /* one to handle all existing RTP flows */